The invention pertains to methods and apparatuses utilized for embossing materials. In particular aspects, the invention pertains to methods and apparatuses utilized for embossing non-woven materials and paper.
Materials can be embossed for one or both of aesthetic and non-aesthetic purposes. For instance, paper webs are frequently embossed during formation of paper products to increase water-holding capacity of the paper products. The same embossing utilized to increase water-holding capacity can also provide a design on the paper product that is aesthetically pleasing to consumers and, in some instances, readily recognized by consumers for product identification and discrimination purposes. In particular aspects, embossing can occur after several plies of a multi-ply paper product are layered atop one another. In such aspects, the embossing can form a pattern of bosses which penetrate the multiple individual plies and holds them together in a final sheet.
Embossing has become a preferred and common practice in many industries. For instance, paper manufactures apply embossing patterns to many of the tissue and towel products currently produced. The patterns will vary from product to product across the manufacture""s product lines, and accordingly each manufacturer will generally have supplies available to produce numerous different embossing patterns. An exemplary application of different embossing patterns is to distinguish premium product lines from non-premium lines. Specifically, the premium products will sometimes have a more complicated embossing pattern than the non-premium products.
Embossing patterns are typically formed with a so-called embossing roll, which is typically a cylinder having an engraved surface. A pattern of projections extend from the engraved surface and are pressed into a paper web to form a boss pattern within the web that is complimentary to the projections extending from the engraved embossing roll.
Engraved embossing rolls are typically expensive to fabricate, and somewhat difficult to replace in a paper-making process. However, as discussed above, paper manufacturers typically have several lines of product, each carrying its own specific boss pattern. Accordingly, the paper manufacturers will have on stock an assortment of engraved embossing rolls, with the individual rolls corresponding to individual distinct patterns of the paper manufacturer""s line of products. The paper manufacturer will then substitute different rolls into a paper-making assembly process when shifting from one line of products to another, or will utilize different dedicated lines. In particular examples, the paper manufacturers will utilize engraved embossing rolls with relatively simple patterns of bosses when making a particular line of product, and will then substitute engraved embossing rolls with more elaborate patterns of bosses when making another line of products. Each substitution carries with it significant expense, as an entire converting process must generally be stopped and restarted during the process of substituting one engraved embossing roll for another. It would, accordingly, be desirable to develop methodologies which can reduce the amount of engraved embossing roll substitutions. Also, as individual engraved embossing rolls are relatively expensive, it would be further desirable to develop methodologies which could reduce the total number of engraved embossing rolls utilized by paper manufacturers in producing their various lines of product.
In another aspect of the prior art, a plurality of embossed plies can be xe2x80x9cmarriedxe2x80x9d together to form a multiply product. An apparatus 200 configured for accomplishing such marrying is described with reference to FIG. 1. Apparatus 200 comprises a pair of engraved embossing rolls (202 and 204), and a pair of rubber-covered backing rolls (206 and 208). Apparatus 200 further comprises a glue applicator roll 210 and a marrying roll 212. In operation, a first paper web 214 is fed between rolls 204 and 208 to emboss a first pattern into web 214, and a second paper web 216 is fed between rolls 202 and 206 to emboss a second pattern into web 216. The second pattern is configured to nest within the first pattern. Accordingly, the patterned web 216 is nested within the patterned web 214, and the two webs are pressed together by marrying roll 212. Glue applicator roll 210 is utilized to provide an adhesive on patterned web 216. Such adhesive is utilized to adhere patterned webs 214 and 216 together.
It could be desirable to incorporate methodologies referred to above for reducing the total number of engraved embossing rolls utilized by paper manufacturers in producing their various lines of product into processes which marry a plurality of plies together.
In one aspect, the invention encompasses a method of utilizing a single engraved embossing roll to emboss different expanses of material with different patterns. The single engraved embossing roll has at least two projections projecting therefrom. A first of the projections projects to a greater height from the roll than a second of the projections.
In another aspect, the invention encompasses method of embossing different expanses of material with different patterns. An engraved embossing roll is provided and a backing roll is provided. The engraved embossing roll has at least two projections projecting therefrom. A first of the projections projects to a greater height from the roll than a second of the projections. The two projections define two distinct patterns. A first of the two distinct patterns comprises both the first and second projections, and a second of the two distinct patterns does not comprise the second projection. A first expanse of material is provided between the engraved embossing roll and backing roll. The engraved embossing roll is pressed against the first expanse to emboss a complementary image of one of the first and second distinct patterns into the first expanse. The first expanse is removed from between the engraved embossing roll and the backing roll. A second expanse of material is provided between the engraved embossing roll and the backing roll. The engraved embossing roll is pressed against the second expanse at a second pressure to emboss an other of the first and second distinct patterns on the second expanse.
In yet another aspect, the invention encompasses an apparatus for embossing different expanses of material with different patterns. The apparatus includes an engraved surface having at least two projections projecting therefrom. A first of the projections projects to a greater height than a second of the projections. The apparatus also includes a backing surface configured to receive the projections of the engraved surface. The backing surface and engraved surface are together configured to receive an expanse of material between them. The apparatus further includes a displacement mechanism configured to move at least one of the engraved surface and the backing surface relative to the other of the engraved surface and the backing surface.